Method and apparatus for producing improved packages

ABSTRACT

There has been provided an improved apparatus for building packages of yarn including a bobbin for taking up the yarn and a reciprocating guide member for reciprocating along the axis of rotation of the bobbin. The guide is driven by a controlled drive at a selected ribbon breaking rate for breaking patterns of ribbon formation. The improvement comprises means adapted to be coupled to the drive for modifying the ribbon breaking rate at a selected frequency modulation rate. The process employing the above apparatus utilizes the improved step of frequency modulating the ribbon breaking rate.

Hooper Oct. 7, 1975 [5 METHOD AND APPARATUS FOR 3,241,779 3/1966 Bray etal, 242/181 PRODUCING IMPROVED PACKAGES 3,402,898 9/l968 Mattingly242/l8.l X 3,434,673 3 /l969 Brouwer et al..... 242/l8.l Inventor: CliveWilliams p 10, 3,514,682 5/1970 Corey 242/l8.l ux Canberra Crescent,Newport, 3,638,872 1/1972 Jennings 242/18.1 Monmouth, England, NPT 3QQ[22 Filed; May 22 1974 Primary ExaminerStanley N. Gilreath Attorney,Agent, or Firm-Cushman, Darby & [21] Appl. No.: 472,419 Cushman RelatedUS. Application Data [63] Continuation of Ser. No, 261,670, June 12,1972, 57 ABSTRACT abandoned, which is a continuation-in-part of Ser. No.167,043, July 28, 1971, abandoned, which is a There has been provldedanImproved apparatus for continuation of Ser. No. 13,802, Feb. 24, 1970,building packages of yarn including a bobbin for takabandoned. ing upthe yarn and a reciprocating guide member for reciprocating along theaxis of rotation of the bobbin. [30] Foreign Application Priority DataThe guide is driven by a controlled drive at a selected Mar. 4, 1969United Kingdom 11490/69 ribbon breaking rate for breaking PatternS ofribbon n formation. The improvement comprises means [52] U.S. c1.242/18.1 adapted to be coupled wthe drive for modifying the [51] Int.Cl. B6511 54/38 ribbon breaking rate at a Selected frequency modula-[58] Field of Search 242/l8.1, 43, 43.1; tion rate- 318/162-164 Theprocess em loying the above apparatus utilizes P the improved step offrequency modulating the ribbon [56] References Cited breaking rate.

UNITED STATES PATENTS 21 Claims, 3 Drawing Flgures 2,763,824 9/l956Bacheler 242/181 X I i M00041? roe US. Patent 00. 7,1975 Sheet 1 0f 23,910,514

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METHOD AND APPARATUS FOR PRODUCING IMPROVED PACKAGES REFERENCE TORELATED APPLICATIONS This application is a continuation of applicationSer. No. 261,670 filed June 12, 1972, now abandoned, which is acontinuation-in-part of an application for IMPROVED PACKAGES, Ser. No.167,043, filed July 28, 1971, now abandoned, which is a continuation ofan application for IMPROVED PACKAGES, Ser. No. 13,802, filed Feb. 24,1970, now abandoned.

BACKGROUND OF INVENTION The present invention relates to the building ofpackages of yarn, string and similar elongate objects and to packages soproduced. It relates particularly, but not exclusively, to the buildingof packages of yarns of textile fibres.

SUMMARY OF INVENTION There has been provided an improved apparatus forbuilding packages of yarn including a bobbin for taking up the yarn anda reciprocating guide member for 'reciprocating along the axis ofrotation of the bobbin.

The guide is driven by a controlled drive at a selected BRIEFDESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view and block diagram ofthe appa ratus of the present invention.

FIG. 2 is a detail of certain aspects of FIG. 1.

FIG. 3 is a circuit diagram showing further details of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT The building of yarn packages isnearly always carried out by rotating a rod, cylinder, cone or similarelongate member, all such being designated by the term bobbin 10 in thisspecification. Said bobbin l0 driven by motor 11 for winding the yarn 12onto said member. Guiding said yarn to and fro parallel with axis ofsaid member is accomplished by a reciprocating guide member 13, called atraverse guide. Said guide 13 is usually located relatively near to thesurface of the rotating bobbin 10 either at a fixed distance therefromor moving gradually away therefrom, in such a way that as the packageincreases in diameter, its surface does not make contact with thetraverse guide. The speed of rotation of the bobbin and the speed,frequency and amplitude of the traverse guide 13 movement may be variednad interrelated in many different ways in order to produce packageshaving various desired characteristics and in order to reduce oreliminate the appearance of certain undesirable phenomena such ridging.The

guide 13 hereinis mounted to channel 14 and is driven in a reciprocatingmanner by drive 17 coupled through control member 18 which engages withthe guide 13 to move it back and forth at selected amplitudes andfrequencies. The amplitude and frequency variations of the guide 13 aregoverned by signals controlling drive 17 from summing amplifier 30, theoperation of which shall be explained further in the specification.

The case of a simple square ended package 10 will be considered here forthe sake of explanation. The shape and structure of the package may,however, be altered greatly from this simple shape in practice, for manyreasons, but such alteration does not vitiate the present invention.

In this specification, the term wind ratio is defined as the package (orbobbin) rotational frequency divided by the traverse frequency.

The traverse frequency is the number of complete traverse cycles made bythetraverse guide 13 per unit time.

A traverse stroke is defined as the distance travelled by the point oflay of yarn 12 onto the bobbin between one point of direction reversalnear an end face and the consecutive point of direction reversal near anend face.

A length of yarn 12 or other elongate object layed upon the package inone traverse stroke will be called a lay.

If said ratio is a ratio of integers, then at regular intervals duringthe package building, certain lengths of yarn will be layed directly (ornearly directly) above one or more other lays previously layed on thepackage, i.e., superimposed thereon. For instance, if the wind ratio isexactly 1, every lay of yarn will in theory be layed precisely. upon apreceding lay. Such a package is obviously undesirable because ribboningoccurs. If the wind ratio is changed from unity to a ratio of smallwhole numbers (integrally related wind ratio) a honeycomb package may beobtained, with lays or parts of lays layed one upon the other along apackage radius at fairly frequent intervals along said radius in arelatively simple pattern.

Such packages may be desirable in some cases, especially when bulk isnot a prime objection or if, for exampmle, it is required to obtainpenetration of some treatment fluid right through the package. Ofcourse, by choosing a suitable constant wind ratio, good packages withother desirable characteristics can be obtained.

There are difficulties, however, associated with the system described,which difficulties increase rapidly with increasing speed of operationof the mechanism used. Some of the main difficulties are associated withthe traverse apparatus itself.

Traversing usually entails moving member 13 rapidly in one direction andthen reversing its direction very rapidly. For this reason it is oftendecided, when working package winding mechanisms at high speeds, to fixthe traverse speed at an optimum value, above and below whichundesirable stresses and strains arise in the apparatus.

In such a case, in order to maintain a constant wind ratio, therotational frequency of the package must be kept constant and this meansthat the peripheral speed of the package will increaseas the packagesize increases. In many cases this is not desirable, because, forinstance, of the danger of increasing tension of the yarn being woundonto the package, so producing a a package with yarn properties varyingthroughout the package. Hence, in general, it is desirable that thepackage peripheral speed remain constant. I

The present description will be made, for simplicity of comprehension ofthe present invention only and in no way limitatively, with reference toa system wherein the bobbin peripheral speed is maintained constant aswell as the traverse speed. This entails a gradual. slowing down of thebobbin l rotational frequency and hence, to the abandonment of a systemhaving a constant wind ratio;

Of course, in practice many much more complicated programmes are used,but the. simple case here described is for simplicity of illustrationonly.

lf the bobbin rotational frequency is, for instance, graduallymonotonically reduced in accordance with increasing radius, the windratio will decrease monotonically and integrally related wind ratios maybe passed through several times during package building. Thus,superimposing of yarn lays or parts of lays will occur to some extent assuch ratios are approached and left behind. Groups of superimposed yarnlays or parts of lays, particularly when lay deflections definedhereinafter occur, will therefore be produced. Troublesome cases inpractice are produced when lays cross over one another whilesubstantially parallel. The most troublesome cases are concerned withlay reversals and such reversal groups will be observable at the ends ofthe package, assuming traverse speed and amplitude are maintainedconstant. Lay crossings and lay crossing groupings may occur at anypoint along lays. Particularly' troublesome are superimposed laydeflection groups. If the programme is complicated, for instance, byslight changes in traverse speed or amplitude, whethersuch changes beexactly repeated or not, some such aforesaid reversal groups may be setback from the package end surfaces and, though not observable, willstill be present.

The aforesaid lay crossings, especially if such crossing is repeated atseveral points along the same packages radius or near it, may producemore or lessobjectionable package surface ridging and other0bjectionable features associated therewith such as periodical variationin take-off tensions when, the yarn is later removed from the package. t

In order to reduce thee objectionable features it has been foundbeneficial to use a short term cyclical variation of traverse speed tomodify a longer term variation of traverse speed or a substantiallyconstant traverse speed. This modifying variation of traverse speedbrings it about that the various undesirable ratios which are gonethrough during package building, exist for shorter periods than withoutit and are distributed more evenly throughout the package.

In particular, those ranges of wind ratios giving honeycomb patterns orcertain ribbon patterns on the surface of the package and correspondingridges on the end faces of the packages are distributed more evenlythrough the packagewhence the method is generally known as ribbonbreaking.

The amplitude and time period of the aforesaid modifying variation oftraverse speed define the ribbon breaking rate and are normally chosenempirically. Such modifying variation will be called hereinafter simplyribbon-breaking. Typical values for ribbon break ingare i variation oftraverse speed according to a triangular, sinusoidal or square waveformwith time, and a cycle time of about 10 0 times the traverse cycle time.It is known to choose the rate of variation of traverse speed in such away that no more than seven lay reversals are laidclose to each other ata time when the wind ratio is close to a ratio of small integers, suchratio giving a honeycomb pattern especially when one integer is unity.

In those cases where package stability approachesits limit, e.g., whenlarge packages arewound at high of constant wind ratio entails thedisadvantage of in- I creasing package peripheral speed or that ofdecreasing traverse speed both, of which entail serious disadvantages athigh operational speeds. Furthermore, with a non-constant wind ratio theridges on the end faces are not reduced to a satisfactory level despitesuch measures the above choice of the ribbon breaking cycle time andamplitude.

It has been found that suitable modification imposed on the aforesaidribbon breaking rate reduces the formation of superimposed yarn laygroups to a surprising degree.

Of course, some modification may occur to a very I small extent due .tovariations brought about by adventitious variations in speed ofmachinery itself. However, the present invention, wherein'such furthermodification of the ribbon breaking rate is strictly controlled in form,velocity and amplitude, gives much more uniform and much morepredictable results than any said adventitious variations.

The modulating apparatus of FIG. 1 generates output signals whicharecoupled through summing amplifier 30 to drive 17 having a staticinverter therein (not shown) which produces an output oscillatorysignal:at a rate governed by modulator 31, for con'troling the tra-. verseguide 13, frequency and amplitude. The electronic system 31 hereinincludes electronic analoge computing circuits used to control thetraverse fre quency in the manner required for yarn lay production inExamples l to 9 described further in the description. The function ofthe elements in this diagram are first described, before consideringtheir operation in more detail.

The traverse drive 17 is governed by outputs of modulation'network 31.In controlling the static inverter in the drive, the frequency of thetraverse 13 corresponds to the frequency of a transistor oscillatortherein (not shown). Thefrequency of this oscillator is determined bythe voltage supplied to it from a summing amplifier I 30. This amplifier30 linearly combines three inputs from preset amplitude controls 32,33and 34 having outputs governed by settings of laycontrol dials 32",

33, 34 which provide respectively, a steady voltage percentage of themean frequency; this in Example l,

the mean traverse frequency has a superimposed deviation of 4% and inExamples 2 9 the deviation from the mean is 10%. The frequency of thistriangular waveform previously described as ribbon breaking is itselfvaried in Examples 1, 3, 5, 8 and 9, and which therefore used a modifiedribbon breaking waveform. To achieve this modification a waveformgenerator 35 is arranged for frequency modulation (as is the transistoroscillator within the static inverter), being fed from a summingamplifier 36 and also from an inverting amplifier 37 which provides asecond input of opposite sign required by the modulation circuit 35.

The summing amplifier 36 linearly combines three inputs from generators38, 39, and 40, having outputs controlled by settings of lay presetcontrols 38, 39' and 40', which provide respectively a steady voltgecorresponding to the mean ribbon breaking frequency (in Examples 1 to 9this is cycles per minute), a triangular waveform (of constant amplitudeand preset frequency), and a noise voltage whose amplitude variesrandomly with time and having an amplitude/frequency spectrum falling'at6db/octave to either side of 0.8Hz. To replace this last triangular(modifying) waveform with noise from the noise generator it issufficient to set a present control 39 to zero (thus removing thecorresponding input to the summing amplifier) and to set control 40' togive the desired amplitude of noise. A noise generator 43 is providedwhich has been described by Yeowart (Electronic Engineering, April,l968, p.212), the output being coupled through a filter 44 giving therequired 6db/octave cut off to eitherside of 0.8HZ.

The third input tosumming amplifier 30 is rectangular waveform derivedfrom thefrequency modulated waveform generator and inphase with the maintri-' angular wave output. lnverting amplifier 41 changes the sign ofthis rectangular waveform and preset control 34 adjusts the amount fedto the traverse drive 17 so as to compensate for the delay of thetraverse mechanism to the change in slope of the triangular (ribbonbreaking) rate at its reversals, and thereby obtain a more rapidreversal of the ribbon breaking waveform.

A control setting indicated by reference numeral 42 is provided for thetriangular waveform generator or oscillator 45 and the noise generator43 can have an adjustable setting to regulate the noise output thereof.

Turning now to a consideratin of FIG. 3, there is shown detailedcircuitry of the arrangement of FIG. 2. The circuitry utilizes nineoperational amplifier circuits labeled A1 through A9 and which areutilized for various functions as hereinafter described. Each oftheseoperational amplifiers can be of the type manufactured by S.G.S.Fairchild Ltd., and designated as No. A702.

The output to the traverse drive unit 17 from summing amplifier 30operates satisfactoraly at 5 Volts maximum means coresponding to maximummean traverse speed. Amplifier A9 is adapted in an Add Mode togetherwith Resistors R28, R29, R30and R31 making up summing amplifier 30. Theamplifier A9 output Here V V and V are the voltages at sliders of therespective control dials 34, 33 and 32" '(VRZS, VR26 and VR27).

By way of Example a 12 volt voltage reference source 47 is providedconnected to VR27, R31 is chosen to equal l0 ohms, R30 2.4 X 10 ohms,R27 5.0 X 10 ohms, and R28 8.0 X 10 ohms and using linear wire woundpotentiometers for the preset controls, their dials (0 to 100 divisions)read 32',33 and 34 respec tively) mean traverse speed as a percentage ofmax value (100 divs max speed), peak to peak traverse speed change (100divisions 40% of max traverse speed), and peak step in demanded traversespeed at reversal of ribbon breaking (100 divisions 10% of max traversespeed). Dials 32', 33, 34, govern the speed settings given in theexamples or could be readily found, whilst the setting of preset 34 maybe determined empirically by observing the waveform of traverse speedagainst time using a recording frequency meter from whose record theribbon breaking reversal time could be found. In this way a triangularwave may be superimposed at a certain percentage on a steady voltage. Todetermine the frequency of the triangular waveform the operation of themain ribbon breaking oscillator 35 is considered.

This frequency modulated oscillator, includes amplifiers A6 and A7functioning as a comparator and as an integrator respectively togetherwith the diode bridge D5, D6, D7 and D8. A bridge driving amplifier Aand a summing amplifier A is in principle the same as A9 alreadydescribed. The output of the comparator A6 is limited by the Zenerdiodes 2;, and Z to 6.8 volts (R ,,=200 ohms as current limit) and,being set to one limit, switches very rapidly to the other when theoutput of the integrator A7 has risen to make the current through Rexceed the magnitude through R the cycle then continuing. The charge anddischarge time of the integrator A7 forgiven values of C resistancechain (R16 (or R17) VR21+ R22) and for symmetrical voltage swing (i 5volts) may bedetermined by the input current through the diode bridge.This in turn may be set by the output voltage from A or A the bridgeselecting the sign of voltage to agree with that of the comparator A6output. The frequency of the frequency modulated oscillator iscontrolled by outputs of the amplifiers A, and A driving the bridgecircuit. In certain of the examples described further in thespecification, the frequency resistances R13, R14, R15, R16 and R17 werechosen to be 10 ohms. A 12 volt voltage reference source 46 is providedconnected to the control setting 38. Setting controls 39' and 40 to Zeroand 38'to divisions (80/100 of full scale 9.6 Volts output), the valueof R10 was adjusted on test (approx. value 2.4 X 10 ohms) to give Aoutput =4 Volts, and the value of R (=10 ohms) was adjusted to give Aoutput +4 Volts. Using C, 10 fd and R22 10 ohms the value ofpotentiometer VR21 was set to approx 2.0 X 10 ohms so as to give anoscillator cycle time of 2 seconds. This corresponded to the oscillatorfrequency of 30 cycles per minute specified in the Examples l to 9 andcould be adjusted by 38 divisions 37.5 cycles/Minute) and checked with adigital frequency meter which was conveniently applied to the zenerdiode pair Z and Z When thefrequency and amplitude of the triangularwaveform from the ribbon breaking oscillator are set inthis way, theoscillator output remains constant at i 5.0 Volts during changes infrequency,

Such changes in frequency are provided, in Example 1, by the triangularwave oscillator (A and A through 7 39, while 40 was set to zero.Similarly in Examples 3, 5,8 and 9,39 was set to zero and 40 was set togive the stated changes in ribbon breaking frequency. In

this way a noise waveformlwas substituted for the triangular waveform.

The oscillator A and A maybe setto give i 5 Volts at a frequency of(30/32) cycles per minute for Example 1. Thus, C was chosen to be '3().tfd and R set at 5.6 X 10 ohms, Z, and Z being 6.8 Volt Zener diodes(as were Z and Z R adjusted in the region of 4.1 X 10 ohms to give 1 5volts at A output and VR4 at an output of amplifier A was set (R, was200 ohms as a current limiter). R1] was chosen to be 2.5 X I ohms,giving 100 divisions (full setting on VR8)-equal to i 40% frequencydeviation of oscillator A., and A for the given setting of 38.

The noise generator 43 supplying A was set to. give 1 volt R.M.S. into Ccorresponding to a range ofinput.

voltages within i-4V peak to peak. C was set to 20 fd and R to It) ohms;R was set to 6.2. X 10 ohms and C to 32 fd, giving the 0.8Hz centerfrequency as required together with a range of noise input i 2.5 Voltsat 40' input. R12 was then chosen tobe 10 ohms giving I00 divisions onVR9 =rt 50% peak frequency deviation. The value of 15%, 25%and 40% usedin Exam ples 6, 5 and 3 and 9 were then obtained'by changing the settingof 40'as required.

The inverting amplifier (41 )A8 was supplied with i 6.8 Volts from zenerdiodes Zgand Z Choosing R24 10 ohms, R23 (about 1.7 X 10 ohms) was seton test to give 4.0 Volts at amplifier A8 output.

The amount by which the conventional ribbon breaking rate is modified isimportant.The percentage modification is defined as the percentagechange about the mean frequency or mean amplitude or both of the ribbonbreaking rate. Preferably such percentage modification lies above 2% andmore preferably between 2 and 50%. A most preferred range is 5 30%.

The present invention, therefore, comprises in one aspect a process forbuilding improved packages of yarn, string or similar elongate object inwhich process the wind ratio varies and wherein a modification isimposed on the ribbon breaking rate as defined hereinbefore whichmodification introduces low frequency components removing at least onecoincidence of lay deflection groups defined hereinafter.

In order to define the characteristics of the aforesaid improvedpackages recourse is bad to the following definitions.

Angle of Lay This is the angle between the direction of lay of the yarnor other elongage object, at any point on the package, and a planenormal to the axis of rotation of the package and passing through saidpoint;

A lay reveral is a special case of a lay deflection, typically occurringat the end face of a package.

Deflection Angle 6 This is defined as the angle at the axis of rotationof the package between the two planesjust containing the lay deflectionand intersecting at said axis of rotation.

Deflection Group A group of consecutive lay deflections such that allsaid deflections lie within an 7 angle 26, where 0 is defined above anddis the mean 0 of the deflection group.

Coincidence of Deflection Groups This is defined as occurring when themean positions of two deflection groups subtcnd an angle (1) at theaxisof rotation of the 7 In another aspect the present inventioncomrises a.

package of yarn, string or similar elongate object in which deflectiongroups are distributed randomly around the circumference of the package,

In yet another aspect the present invention comprises a package of yarn,string or other elongate object wherein there is substantially nocoincidence of deflection groups as defined hereinbefore.

The, aforesaid modification to the conventional rib bon breaking ratecanbe regarded, generally, as the ad dition of other, and particularlylower, frequencies so as to make. a more complex wave form. Suchmodification may. be achieved, for example. by the addition of modulatedtriangular, or sinusoidal waveforms or of random noise previouslymentioned. Furthermore, it may be achieved by modulation either in termsof amplitude or frequency of traverse, both of these being special casesof the addition of other frequencies.

' It has been found that amplitude modulation while of use in somecases, is considerably less effective than frequency modulation, becausethe basic repetition time remains unaltered and so wind ratio transitsoccurring close to the the mean value of the ribbon breaking rate willnot be greatly altered in position by amplitude modulation.

One possible method of achieving modification of the ribbon breakingrate is to frequency modulate theribbon breaking rate according to asecond, longer period, triangular or sinusoidal waveform. Whilst thismethod gives an improved package, it nevertheless has the disadvantageof retaining a longer-period cyclical relationship between the packagerotation time, the ribbon breaking .cycle time and the modulation cycletime. This is particularly disadvantageous when package building lastsfor a long time, for instance when building packages of 'a very fineyarn. I

A further increase in the duration of said longerperiod relationship canbe obtained using frequency modulationwhich, in Fourier analysis terms,contains lower frequency components. Such a modification imposes waveforms which when frequency analyzed in a Fourier .series contains lowerfrequency components than those in a similar series for the unmodifiedwave-- form. Such a waveform may be obtained. for example,

' by adding together two or more triangular or sinusoidal waveformshaving successively lower frequencies, each being typically between /1and H10 of the next higher frequency in the set of modulationfrequencies, the highest being similarly related to the mean ribbonbreaking frequency. The effectiveness of such a waveform is increased ifthe several waveform generators employed have cycle times which do notrepeat exactly or have noise components. It is also possible to replacepart or all of such modification frequency generators by a random noisegenerator. The frequency range within which energy from the noisegenerator is supplied to the ribbon breaker modulation system extendsdownwards from a value corresponding typically to about A; to 1/10 ofthe mean ribbon'breaking cycle or from the lowest frequency in the abovedescribed set of one or more modulation frequency generators, to a lowerlimit of frequency the cycle time of which is at least greater than thetime necessary to allow the rate of growth of package diameter to causea change in the package rotation period sufficient to disturb theintegral relationship between ribbon breaking cycle and packagerevolution time.

The actual means of achieving theobjects of the present invention dependon the design of the package and the winding equipment on which it isintended to be used. It has been found particularly convenient,especially in view of the convenience of use of an electronic randomnoise generator, to use electrical signals for the modifying waveformsas shown in the drawing. Mechanical or hydraulic generators could, ofcourse, be used if more adaptable to the winding equipment in use.

The following examples are for illustration only and in no waylimitative of the invention.

EXAMPLE 1 The packages produced were wound at 9,500 feet per minute frommultifilament nylon 6.6. yarn of 205 denier and containing 34 filamentswith a inch peakpeak traverse The approximate parameters of thevariation in traverse cam speed are as follows:

2. Peak to peak variation 3. Mean frequency of variation 4. Percentagemodulation 5. Modulationfrequency 6. Calculated maximum rate of changeof cam speed.

7. 'lraverse cam speed reversal time (time from turning point to camspeed change completion.)

160 milliseconds.

Packages were made both with and without the mod-- ulation described initems 4 and 5 above. The packages made with modulation were considerablyless ridged on the end faces than those made without. Examination of theprocess to show the distribution of deflection groups showed that fewercoincidences of deflection groups took place with the above-definedmodulation.

EXAMPLES 2 9 The process of example 1 was repeated, but instead of thetriangular wave, noise from waveform generator 43 was superimposed atvarious levels. The generator 43 contained a filter (not shown) whichproduced a spectrum whose envelope fell off at 6 decibels per oetave oneither side of 0.8 Hertz (cycles per second).

Furthermore, the packages were wound at 2700 feet per minute, with thefollowing parameters:

Traverse stroke 5V2" length Container diameter 4V2 Package weight 4.72lbs. Outside package diameter 7% Winding tension The results are shownin Table l.

22 gms: constant In the case where noise was superimposed on the ribbonbreaking waveform the following variation parameters pertained:

Mean frequency of variation of ribbon breaking waveform 30 cycles/min.

Mean amplitude variation of ribbon breaking waveform 10% end face butslightly more than in example 8.

From the results given in Table 1 it can be seen that 25% modificationby the noise generator gives a considerable improvement in ridging ofthe package endface, which is a measure of deflection group coincidence.

As expected from prior art, and as shown by comparison of examples 6, 4and 2, an improved appearance of the end faces was obtained by anincrease in traverse speed, which is undesirable. A relative increase intraverse speed can be obtained by decreasing the yarn speed but this isalso undesirable from the productivity viewpoint.

The imposition of 25% modification with traverse speeds of both 475 and415 c.p.m. produced a considerably improved end face.

It is known to decrease end face rigidness by sharpening the ribbonbreaking waveform (i.e. reducing traverse cam reversal time) and thiswas done in examples 7 9. Comparison of examples 6 and 7 shows theexpected improvement. Example 8 shows that still further improvement isobtained by the imposition of 15% modification. When the percentage isincreased to 40% there is still a better appearance than with no imposedmodification but the results are not quite so good as with 15%.

Furthermore, whilst the present invention has been particularlydescribed with reference to the building of packages of yarn it canclearly be applied to the building of packages of any other elongateobjects such as wire, string and the like.

While there has been described what at present is the preferredembodiment of the present invention, it will be obvious to those skilledin the art that various changes and modifications may be made hereinwithout departing from the invention and it is extended in the appendedclaims to cover all such changes and modifications as come within thescope of the present invention.

What is claimed is:

1. An improved control for use with apparatus for winding yarn on abobbin including a drive means for driving the bobbin, a traversingmechanism for repetitively traversing the yarn axially along the surfaceof the bobbin during wind up, and control means for the.

traversal mechanism for generating a rate control sig nal for drivingthe mechanism at a selected rate, said control means including meanssetting a mean driving rate signal as part of said rate control signal,ribbon breaking rate means for continuously generating a relatively longterm cyclically varying signal as part of said rate control signal forvarying the rate control signal between predetermined fixed limitsrespectively above and below the mean driving rate signal, and whereinsaid control means further includes modifying means for continuouslygenerating a relatively short term varying signal as part of said ratecontrol signal for continuously modifying the rate at which the ratecontrol signal is varied between the predetermined fixed limits.

2. The apparatus as described in claim 1 wherein said modifying meanscomprises an oscillator for producing a modulating signal, therebyproducing continuous modulation of the relatively long ,term cyclicallyvarying signal between the fixed predetermined limits.

3. The apparatus as described in claim 2 wherein said modulating signalcomprises a triangular wave form.

4, The apparatus as described in claim 2 wherein said modulation signalcompries a sinusoidal wave form.

5. The apparatus as described in claim 2 wherein said modulation signalcomprises random noise signals.

6. The apparatus described in claim 2 wherein said modulation comprisesmodulation of said long term cyclically varying signal at leastgreaterthan 2 percent.

7. The apparatus as described in. claim 2 wherein said modulationcomprises modulation of said long term cyclically varying signal between2 and 50 percent.

8. The apparatus asdescribed in claim 2 wherein said modulationcomprises modulation of said long term cyclicaily varying signal between5 and 30 percent.

9. The apparatus as described in claim 2 including means for varying thefrequency and amplitude of said modulating signal.

10. The apparatus described in claim 2 wherein said oscillator includesfirst, second and third means respectively adapted for generating atriangular waveform, a sinusoidal waveform and random noise outputs,

amplitude control means for each first, second and third means adaptedfor controlling the amplitude for its respective output and frequencycontrol means for each first, second and third means adapted ,to controlthe frequency thereof.

11. The apparatus as described in claim including summing means adaptedto be selectively coupled between the outputs of said first, second andthird means and said traversal mechanism, said selected rate varied inaccordance with said summed outputs.

12. A process for building packages, of yarn, string and similarelongate objects in which a bobbin is supplied with yarn and is drivenat a selected speed and a traversing mechanism repetitively traversesthe yarn axially along the surface of the bobbin during the wind up at aselected traverse rate comprising the steps of i cyclically'andcontinuously varying the traverse rate between fixed predeterminedlimits on each side of a mean traverse rate to define a ribbon breakingtraverse rate, and continuously modifying the ribbon breaking traverserate by modulating it with a short term varying 1 signal to vary theribbon breaking traverse rate between the fixed predetrmined limits.

13. The processas described in claim 12 wherein said modulation of theribbon breaking traverse rate comprises frequency modulation thereof.

14. The process described in claim 12 wherein the step of modulating theribbon breaking traverse rate is carried out with a short term varyingsignal having a frequency and amplitude such that the modulated rib bonbreaking traverse rate contains lower Fourier series frequencycomponents than an unmodulated ribbon breaking traverse rate.

15. The process described in claim 12 wherein said step of modulation isperformed with a triangular wave-, form modulating signal.

16. The process as described in claim 12 wherein said step of modulationis performed with a sinusoidal waveform modulating signal.

17. The process described in claim 12 wherein said step of modulation isperformed with a random noise modulating signal.

18. The process as described in claim 12 wherein said modulation of saidribbon breaking traverse rate is carried out to an extent sufficient toproduce between 2 andSO percent modulation thereof.

19. The process as described in claim 12 wherein said modulation of saidribbon breaking traverse rate is carried out to an extent sufficient toproduce between 5 and 30 percent modulation thereof.

20. The process as described in claim 12 wherein said modulation iscarried out with a modulating signal which is the sum of a triangularwaveform signal, a sinusoidal waveform signal and a random noisewaveform signal.

21. The process as described in claim 20 including the step ofselectively varying the frequency and amplitude of each of saidtriangular, sinusoidal and random noise signals.

1. An improved control for use with apparatus for winding yarn on abobbin including a drive means for driving the bobbin, a traversingmechanism for repetitively traversing the yarn axially along the surfaceof the bobbin during wind up, and control means for the traversalmechanism for generating a rate control signal for driving the mechanismat a selected rate, said control means including means setting a meandriving rate signal as part of said rate control signal, ribbon breakingrate means for continuously generating a relatively long term cyclicallyvarying signal as part of said rate control signal for varying the ratecontrol signal between predetermined fixed limits respectively above andbelow the mean driving rate signal, and wherein said control meansfurther includes modifying means for continuously generating arelatively short term varying signal as part of said rate control signalfor continuously modifying the rate at which the rate control signal isvaried between the predetermined fixed limits.
 2. The apparatus asdescribed in claim 1 wherein said modifying means comprises anoscillator for producing a modulating signal, thereby producingcontinuous modulation of the relatively long term cyclically varyingsignal between the fixed predetermined limits.
 3. The apparatus asdescribed in claim 2 wherein said modulating signal comprises atriangular wave form.
 4. The apparatus as described in claim 2 whereinsaid modulation signal compries a sinusoidal wave form.
 5. The apparatusas described in claim 2 wherein said modulation signal comprises randomnoise signals.
 6. The apparatus as described in claim 2 wherein saidmodulation comprises modulation of said long term cyclically varyingsignal at least greater than 2 percent.
 7. The apparatus as described inclaim 2 wherein said modulation comprises modulation of said long termcyclically varying signal between 2 and 50 percent.
 8. The apparatus asdescribed in claim 2 wherein said modulation comprises modulation ofsaid long term cyclically varying signal between 5 and 30 percent. 9.The apparatus as described in claim 2 including means for varying thefrequency and amplitude of said modulating signal.
 10. The apparatus asdescribed in claim 2 wherein said oscillator includes first, second andthird means respectively adapted for generating a triangular waveform, asinusoidal waveform and random noise outputs, amplitude control meansfor each first, second and third means adapted for controlling theamplitude for its respective output and frequency control means for eachfirst, second and third means adapted to control the frequency thereof.11. The apparatus as described in claim 10 including summing meansadapted to be selectively coupled between the outputs of said first,second and third means and said traversal mechanism, said selected ratevaried in accordance with said summed outputs.
 12. A process forbuilding packages of yarn, string and similar elongate objects in whicha bobbin is supplied with yarn and is driven at a selected speed and atraversing mechanism repetitively traverses the yarn axially along thesurface of the bobbin during the wind up at a selected traverse ratecomprising the steps of cyclically and continuously varying the traverserate between fixed predetermined limits on each side of a mean traverserate to define a ribbon breaking traverse rate, and continuouslymodifying the ribbon breaking traverse rate by modulating it with ashort term varying signal to vary thE ribbon breaking traverse ratebetween the fixed predetrmined limits.
 13. The process as described inclaim 12 wherein said modulation of the ribbon breaking traverse ratecomprises frequency modulation thereof.
 14. The process as described inclaim 12 wherein the step of modulating the ribbon breaking traverserate is carried out with a short term varying signal having a frequencyand amplitude such that the modulated ribbon breaking traverse ratecontains lower Fourier series frequency components than an unmodulatedribbon breaking traverse rate.
 15. The process as described in claim 12wherein said step of modulation is performed with a triangular waveformmodulating signal.
 16. The process as described in claim 12 wherein saidstep of modulation is performed with a sinusoidal waveform modulatingsignal.
 17. The process as described in claim 12 wherein said step ofmodulation is performed with a random noise modulating signal.
 18. Theprocess as described in claim 12 wherein said modulation of said ribbonbreaking traverse rate is carried out to an extent sufficient to producebetween 2 and 50 percent modulation thereof.
 19. The process asdescribed in claim 12 wherein said modulation of said ribbon breakingtraverse rate is carried out to an extent sufficient to produce between5 and 30 percent modulation thereof.
 20. The process as described inclaim 12 wherein said modulation is carried out with a modulating signalwhich is the sum of a triangular waveform signal, a sinusoidal waveformsignal and a random noise waveform signal.
 21. The process as describedin claim 20 including the step of selectively varying the frequency andamplitude of each of said triangular, sinusoidal and random noisesignals.